Our new type of camera module is small and thin, and is able to detect the distances of objects as well as their images. The module comprises a four-lens array, one imaging sensor and optical filters. The imaging sensor is divided into four areas, two of which are covered with green filters and the other two with infiared filters. A prototype was fabricated with a focal length of 2.63 mm and a baseline length of 2.59 mm. The two images with the same optical filters have parallax, so the distances of objects can be calculated by comparing the two images. We use infrared images illuminated with infrared LEDs at night, and green images during the daytime. After calibrating the images, we achieved a distance-detection accuracy of within ±2.5% at 1 m in spite of the camera's small baseline length. Consequently, our new distance detection camera module is small and thin, and generates a depth-image of an object as well as its image. Our camera module is thus applicable to vehicles, security systems and three-dimensional imaging.
Our new type of camera module has a four-lens-array and an imaging sensor. The imaging sensor is divided to four regions, and these four regions are aligned in one-to-one correspondence with the four lenses. Four color filters are placed over the four imaging regions. First region has a blue filter, second has a red, and the other two have green filters, and two regions with green filters are aligned diagonally. Diffraction gratings are formed on aspheric surfaces of the four lenses, and MTF characteristics of these lenses are improved. The four images taken through the different lenses have parallax, but these parallaxes can be calculated by comparison of the two green images. Pixel shifts of blue, red and green images are realized by rotating the four-lens-array slightly with respect to the imaging sensor. After correcting the parallaxes, the green image, the parallax-corrected blue image and the parallax-corrected red image are composed to generate the resultant color image with high resolution. Distances between objects and the four-lens-array are detected by use of the above parallaxes, and measurement error is less than 2.5% for near objects. With above configuration and functions, our camera module has realized smaller height, higher image resolution and distance-detection capability, and will be applied for cellular phones and automobile vehicles.